Processes for removing potassium from potassium-bearing molybdenum trioxide using an acid leach process are known. See, for example, U.S. Pat. No. 4,612,172 to Brunelli et al., which is assigned to the assignee of the instant invention.
Small amounts (as little as 100 parts per million) of potassium which remain in the molybdenum trioxide have a detrimental effect on the sintering of pure molybdenum powder. The presence of potassium in molybdenum powder which is to be sintered contributes to a lower sintered density in the final molybdenum part. Lower density of sintered molybdenum parts contributes to decreased strength and greater incidence of breakage.
Brunelli et al. report that excessive molybdenum losses will accompany the removal of potassium if the weight ratio of the acid leach solution to the molybdenum trioxide exceeds about 4.8 to 1.
It would be an advantage in the art to develop a process for removing even greater amounts of potassium from potassium-bearing molybdenum trioxide than is currently possible under the Brunelli et al. method while minimizing the loss of molybdenum.